Forced oil transformer



June 23, 1925.

' L. H. BURNHAM FORCED OIL TRANSFORMER Filed Feb. 27, 1922 Inventor:Locke H .lsurnharr His Attorney Patented June 23, 1925.

UNI ED STATES PATENT orncs.

LOGKE H. BUBIIKAI, OF PITTSmD, IASSACHUSBTTS, ASSIGNOR TO GENERAL ELEC-TRIO OOIPANY, A CORPORATION 01 NEW YORK.

I'OBCED OIL Tamar-0am Application fled February 27,1982. Serial No.589,650.

To all whom it may concern:

. Be it known that I, Locxn H. BURNHAM, a citizen of the United States,residing at Pittslield, county of Berkshire, State of Massachusetts,have invented certain new and useful Improvements in Forced OilTransformers, of which the following is a specification.

My invention relates to electric transformers and more particularly toan improved construction and arrangement of parts ada ted to prevent theoccurrence of undesirabfy high temperatures within such transformers.When a transformer is oper ating under load, heat is generated in thecore and windings which assume temperatures dependent upon the amount ofheat generated and upon the rate at which the heat is removed from them.Obviously, the more rapidly this heat is removed from the transformerarts, the greater will be the load which t e transformer can carry for agiven maximum rise in'temperature. The general object of the presentinvention is to provide an improved construction whereby the heatgenerated in a transformer may be rapidly and efliciently removed sothat the transformer ma be heavily loaded without danger of its beingsubjected to undesirable temperatures.

Transformers are often immersed in an insulating fluid such as asuitable oil having high dielectric strength. This fluid penetrates theopenings and interstices of the transformer and serves not only asinsulation but also as a heat absorbing medium. It is important,however, that the fluid be not only permitted to reach all heated partsof the transformer but also that it be free to circulate readil so as tocarry away rapidly the heat w ich it has absorbed from those parts. Oneof the objects of the invention is to provide a transformer immersed inan insulating and cooling fluid and so constructed that currents of thefluid will be thoroughly distributed among and through these parts. Afurther object of the invention is to provide an improved means forsupplying t e cooling fluid to the transformer.

In order to illustrate the principles of the invention, one embodimentthereof is shown in the accompanying drawin in which Fig. 1 is a view inelevation of a t 0 phase transformer with a cooling system constructedin accordance with the invention, the view being partly in section toshow details of construction; I ig. 2 is a plan view of the transformerand cooling system shown in Fig. 1; Fig. 3 is a perspective view of adetail of the cooling system; and Figs. 4 and 5 are elevations ofspacing members used in the coil stacks of the transformer.

Like reference characters refer to similar parts in the differentfigures of the drawmg.

In the particular embodiment of the invention shown in the drawing, athree phase transformer including a three legged core 1 with windings 2on each leg is enclosed in a tank or casing 3 adapted to hold a body ofinsulating and cooling fluid 4 in which the transformer is immersed. Thestack of windings2on each leg are of the interleaved disc coil type.Each coil is enclosed in a casing or wrapping 5, the casing on each coilbeingspaced from one or both faces of the coil by a flat annularinsulating disc 6 which is in turn spaced from the face of the coil byradially disposed spacers 7 formed with transverse openings or notches 8as indicated in Fig. 2 and as shown clearly in Figs. 4 and 5. By thisarrangement, each set of spacers 7 serves to maintain a series ofradially disposed spaces 9 between each of the annular discs 6 and theadjacent coil surface, these radially disposed spaces being allconnected together by the openings or notches 8 in the spacers 7 A fluidconductor or pipe 10 is supported longitudinally of each 0011 stack andalong its outer face. The side of each pipe 10 toward the coil stack isprovided with a slot or opening 11 opposite which the casing or wrapping5 is removed from the coils composing the winding 2, thus providingentrance openings from the pipes 10 to the spaces 9 between the annulardiscs 6 and the coils. Another narrow longitudinal section of eachcasing 5 is also removed from each coil stack, preferably substantiallyopposite the pipe 10 in each case, thus forming exit openings 12 fromthe spaces 9 to the main body of fluid 4 surrounding the coil stacks.One end of each of the pipes 10 is connected by a supply pipe 13 with afluid pump 14, the opposite ends of the pipes 10 being close Oil orother insulating and cooling fluid which may permit suflicient coolingof this 45 supplied under pressure from the ump 14 will flow through thepipe 13 and t e pipes 10 into and through all the spaces 9, fin lyemerging from the coil stacks through the openings 12 and mingling withthe main 'body of fluid 4 surrounding the windings in the tank 3. Fromthe casing 3, the fluid is conducted back to the intake of the pump 14through pipes 15 and a cooler 16. This cooler is shown as comprising anouter casing through which the fluid flows and an enclosed coil of pipe17 adapted to conduct a cooling current of some suitable fluid such aswater to reduce the temperature of the current of warmed fluid returningfrom the transformer to the pump.

In order that the current of cooling fluid passing through the coilstacks of the transformer may be thoroughly distributed over thesurfaces of the transformer coils, the openings or notches 8 in thespacers 7 may be disposed in staggered relation in successive spacers asindicated in Fig. 2 and also in Figs 4 and 5, these latter figuresshowin two successive or adjacent spacers remove from one of thetransformer coil stacks. Another advantage attained by staggering thenotches 8 is the assurance of su port for each turn of the coil at leastas o ten as at every second spacer. The turns of the con ductor are ofcourse substantially concentric with the axis of the coil and it isobvious that, with the notches 8 staggered in successive spacers, anyturn of the coil which lies opposite a notch in one spacer willescapethe notches in the next spacer in either direction. A set ofspacers 7 is provided for both faces of each winding 0011 except that,as indicated in Fig. 1, the spacers may be omitted if desired from theouter face of each end coil. Here, the coil surface is separated fromthe main body of cooling fluid 4 only by the casing or wrapping 5 coilsurface.

In the particular construction shown in the drawing, the openings 12throu h which the cooling fluid leaves the coil are all disposed so thatthe fluid is discharged from the stacks at one side of the tank 3 andthe pipes 15 are so dispomd that the fluid leaves the tank fromconvenient points at the opposite side of the tank after flowing alongthe outer surfaces of the coil stacks.

What I claim as new and desire to secure by Letters Patent of the UnitedStates, is

1. The combination with a transformer of an enclosing tank con coolingfluid in which the transformer is immersed, said transformer including aplurality of disc coils, radially arranged spacers between said coils,said spacers being constructed and arranged with openings respectivelystaggered in adjacent spacers, means enclosing said coils and spacers,said enclosing means having entrance and exit openings to permit thecooling fluid to enter and leave the spaces between the coils, meansincluding a fluid cooling device outside said tank, and means forconducting cooling fluid from said cooling device to said entrance 0nings and from said tank back to said coo ing device.

2. The combination with a transformer of an enclosing tank containingcooling fluid in which the transformer is immersed, said transformerincluding a plurality of disc coils, each of said coils having spacersbetween one of its faces and the adjacent coil, each coil and itsspacers being enclosed in an individual casing having entrance and exitopenin for cooling fluid, and means for conducting cooling fluid to saidentrance openings.

In witness whereof, I have hereunto set my hand this 24th day of Feb.,1922.

LOGKE H. BURNHAM.

